1. Field of the Invention
The present invention relates generally to processors and computer systems and more particularly to a computer system and method of using temperature measurements to detect and to respond to user activity levels.
2. Description of the Related Art
Power management and power efficiency is an important feature for many types of modern computer systems. Power efficiency is especially important for mobile computers and other mobile devices that contain computer processors. For such systems, battery life is an important aspect of the usefulness of the device.
For example, a conventional notebook computer (also commonly referred to as laptop or portable computer) has power and thermal constraints that cause it to operate at performance states below an equivalent desktop computer.
Many power saving techniques have been introduced to try and mitigate the impact of thermal and battery power constraints. The frequency of operation (clock frequency) of the processor and its operating voltage determines its power consumption. Since power consumption and therefore heat generation are roughly proportional to the processor's frequency of operation, scaling down the processor's frequency has been a common method of staying within appropriate power limitations. Microprocessors utilized in mobile applications, i.e., those used in battery powered systems, are particularly sensitive to power considerations and therefore generally require the lowest supply voltage that can achieve the rated clock speed. That is in part due to the small, densely packed system construction that limits the ability of the mobile computer system to safely dissipate the heat generated by computer operation.
A common power management technique called “throttling” prevents the processor from over heating by temporarily placing the processor in a stop grant state. During the stop grant state the processor does not execute operating system or application code and typically has its clocks gated off internally to reduce power consumption. Throttling is an industry standard method of reducing the effective frequency of processor operation and correspondingly reducing processor power consumption by using a clock control signal to modulate the duty cycle of processor operation. A temperature sensor monitors the processor temperature to determine when throttling is needed. Throttling continuously stops and starts processor operation and reduces the effective speed of the processor resulting in reduced power dissipation and thus lowering processor temperature.
In addition, users of computer systems desire increased speed and operating performance as well as long battery life. The conventional throttling power management method has an undesirable effect of reducing processor performance by reducing the effective processor speed. Accordingly, there is a need for an improved system and method to address power management of computer systems.